Broadband Anti-Reflective Titanium Surfaces Fabricated by Hybrid Femtosecond Laser and Electrochemical Anodization

Reducing the optical reflectance of titanium surfaces is critical for stealth-related applications, yet achieving broadband anti-reflection without using hazardous fluoride electrolytes remains challenging. In this work, a hybrid strategy combining femtosecond laser texturing and fluoride-free anodization was developed to fabricate hierarchical micro/nano anti-reflective structures on pure titanium. Periodic grid microstructures generated by laser processing provided geometric light trapping, while subsequent anodization introduced nanoscale porous features that further modulated the effective refractive index. Surface morphology, chemical composition, reflectance, and electrochemical behavior were systematically characterized. The optimized hierarchical surface achieved a minimum average reflectance of 2.29% over the wavelength range of 200 to 2500 nm, corresponding to a 93.4% reduction compared with untreated titanium, demonstrating the synergistic anti-reflective effect of the micro-nano architecture. This work offers an environmentally friendly and scalable route for engineering multifunctional titanium surfaces with broadband anti-reflective properties.